East African Journal of Sciences (2018) Volume 12 (2) 111-126 ______________________________________________________________ Licensed under a Creative Commons *Corresponding Author. E-mail: abrahamgdr@gmail.com Attribution-NonCommercial 4.0 International License. ©Haramaya University, 2018 ISSN 1993-8195 (Online), ISSN 1992-0407(Print) Effect of Integrating Variety, Seed Treatment, and Foliar Fungicide Spray Timing on Managing Common Bean Anthracnose at Bako, Western Ethiopia Abraham Negera*1 and Mashilla Dejene2 1Oromia Agricultural Research Institute, Bako Agricultural Research Center P.O. Box 03, Bako, Ethiopia 2School of Plant Sciences, Haramaya University, P.O. Box 138, Dire Dawa, Ethiopia Abstract: Bean anthracnose [Colletotrichum lindemuthianum (Sacc. And Magn.) Lams.-Scrib] is one of the major diseases of common bean (Phaseolus vulgaris L.), and causes huge yield losses in western Ethiopia. The research was conducted at Bako during 2014 main cropping season with the objectives to: 1) assess the efficacy of seed treatment and foliar fungicide spray timing; 2) determine the effect of integrated use of common bean varieties, seed treatment and foliar fungicide spray timing on anthracnose severity, yield and yield components; and 3) assess the economic feasibility of the treatments. The treatments consisted of three bean varieties (Awash Melka, Awash-1 and Mexican 142), two levels of seed treatment (thiram-treated at the rate of 5 g kg-1 seed and non-treated) and four foliar spray timing with tebuconazole at the rate of 350 ml ha-1 (at the fifth trifoliate, flowering, pod setting stages and unsprayed control). The experiment was laid out as a randomized complete block design (RCBD) in a factorial arrangement and replicated three times per treatment. Disease parameters were assessed from 18 pre-tagged plants per plot; yield components were assessed from ten randomly pre-tagged plants; seed yields were recorded from plants in the three central rows in each plot. Variety, seed treatment, and foliar spray timing interacted significantly (p  0.05) to influence foliage and pod disease severity index, area under the disease progress curve (AUDPC), infected pod per plant and seed yield. Awash-1, without seed treatment and without foliar spray, showed the highest (86.0%) foliage severity and the highest (71.32%) pod severity with calculated AUDPC values of 2771.19 and 1150.25%-days for leaf and pod, respectively. Mexican 142 from treated-seed and sprayed with tebuconazole at the fifth trifoliate stage produced the highest (2354.074 kg ha-1) seed yield, followed by Awash-1 (2239.76 kg ha-1) from non-treated seed and sprayed starting at the flowering stage. The highest marginal rates of return of 3071 and 2568% were calculated for Awash-1 without seed treatments but sprayed at flowering and pod setting, respectively, followed by Awash Melka (1962%) that was sown without seed treatment but sprayed at the flowering stage. Therefore, Awash-1 and Awash Melka without seed treatment and spraying with tebuconazole at the flowering stage resulted in the optimum yields of the crop, indicating that these treatments could be practiced as the most effective management measures against common bean anthracnose for sustainable production of the crop in the study area and elsewhere with similar agroecologies. Keywords: Area under the disease-progress curve (AUDPC); [Colletotrichum lindemuthianum (Sacc. and Magnus) Lams.-Scrib]; Phaseolus vulgaris L.; foliar spray timing seed treatment 1. Introduction Common bean (Phaseolus vulgaris L.) is an important legume crop in the daily diet of more than 300 million of the world’s population (Hadi et al., 2006). It has been rated as the second most important source of human dietary protein and the third most important source of calories of all agricultural commodities produced in eastern Africa (Pachico, 1993). Common bean production in the Central Rift Valley of Ethiopia contributes to about 60% of the total common bean production in the country (Aleligne, 1990). Common bean is grown usually as mixed varieties in most of southern, eastern, and western parts of the country (Mohammed and Somsiri, 2005). The yields of common beans are about three times as high in developed countries, such as USA and Canada, compared to the developing countries (Porch et al., 2013). The national average yield of common bean in Ethiopia is low and it was estimated at 1.41 t ha-1 in 2015/2016 cropping season (CSA, 2016); seed yields of improved varieties on research fields in Ethiopia ranged from 2.5 to 3.0 t ha-1 (EPPA, 2004). There are various production constraints that contribute to the low yields of common bean in the country. Diseases are known to be the major factors that, directly or indirectly, affect the production of the crop. The major diseases that are currently threatening common bean production in Ethiopia include anthracnose [Colletotrichum lindemuthianum (Sacc. And Magnus) Lams.-Scrib], rust (Uromyces appendiculatus F. Strauss), common bacterial blight (Xanthomonas axonopodis pv. phaseoli), halo blight (Pseudomonas syringae pv. phaseolicola), angular leaf spot mailto:abrahamgdr@gmail.com Abraham and Mashilla East African Journal of Sciences Volume 12 (2) 111-126 112 (Phaeoisariopsis griseola Sacc. Ferr), Ascochyta blight (Ascochyta phaseolorum Sacc.) and bean common mosaic virus. Anthracnose, rust, angular leaf spot and common bacterial blight are more important than other common bean diseases and are widely distributed, while the rest are much more restricted in specific growing areas in their distribution (Habtu, 1987; Habtu and Abiy, 1995; Habtu et al., 1996; Odogwu et al., 2016). Bean anthracnose is the most serious disease of common bean in the cool weathers in Latin America and Africa. In these parts of the world, the field losses ranged from 90 to 100% due to seedling, leaf, stem and pod infection under climatic conditions favorable to the disease (Nyvall, 1989; Padder and Sharma, 2017). The infected seeds are the most important means of dissemination of Colletotrichum lindemuthianum (C. lindemuthianum), which explains its worldwide distribution (Allen et al., 1996). The crop is vulnerable to the pathogen at all stages of growth, from seedling to maturity, depending on the prevailing environmental conditions that favor initiation and further development of the pathogen. The disease causes an estimated common bean yield loss of 63-100% in Ethiopia (Tesfaye, 1997; Kutangi et al., 2010; Amin et al., 2014), but there is variation from one region to another. For instance, 42.4% yield loss was reported for Haramaya district (Amin et al., 2013) and 11.9% for Bako area from infection of free seeds and 20% from infected seeds (Mohammed and Somsiri, 2005). Also the planting value of harvested seed is reduced due to decreased germination and poor quality (Singh and Schwartz, 2010). Management strategies used to minimize seed-borne infection due to C. lindemuthianum in the seed production fields include cultural, host resistance, biological, and chemical protection methods. Although the infected seeds are the most important means of dissemination of C. lindemuthianum (Allen et al., 1996), the pathogen affects the crop at all stages of growth. Therefore, it is necessary to understand the interaction between common bean and the pathogen at different developmental stages of the crop to design sustainable disease management strategies. Moreover, integrated disease management is the most recommended option for such diseases in which infection due to the fact that pathogen occurs starting from the seed to all growth stages of the crop, and due to the high diversity of the pathogen (Allen et al., 1996). However, integrating host resistance, seed treatment and foliar application of fungicides at different growth stages of the crop was not studied well in Ethiopia. Therefore, this study was conducted with the objectives to elucidating the effect of integrating common bean variety, seed treatment, and foliar fungicide spray timing on the severity of common bean anthracnose and yield and yield components of the crop as well as to assess the economic feasibility of the different treatment combinations. 2. Materials and Methods 2.1. Description of the Study Site The study was conducted at Bako Agricultural Research Center (BARC) in western Ethiopia during the 2014 main cropping season. Bako Agricultural Research Center (BARC) has warm, humid climate with 54 years mean minimum, maximum and average temperatures of 13.3, 28.0 and 20.6 oC, respectively, and 48 years mean relative humidity of 63.55% (BARC, 2014). The averages of seven days interval rainfall and temperature during the production period are depicted hereunder (Figure 1). Figure 1. Weather data of Bako during 2014 cropping season a. Experimental Materials i. Common bean varieties The three Malkasa Agricultural Research Center released white seed-canning type common bean varieties, namely Mexican 142, Awash 1 and Awash Melka, released in 1973, 1990 and 1998/99, respectively, were used in this experiment. The varieties have been recognized to possess different susceptibility levels, viz. Mexican 142 is moderately susceptible, and Awash-1 and Awash Melka are susceptible and tolerant, respectively, for the disease anthracnose caused by C. lindemuthianum (Sacc. and Magnus) Lams.- (Kutangi, et al., 2010; BARC, 2013). ii. Fungicides The fungicide used in seed treatment is a protective fungicide, commonly known as thiram 75 WP and chemically known as tetramethyl thiuram disulfide. The broad spectrum systemic fungicide Tebuconazole 430 SC, commonly known as Orius 25 EW, was used for foliar spray to manage common bean anthracnose. b. Treatments and Experimental Design The treatments consisted of four spray application timing of foliar fungicide (Tebuconazole, syn. Folicur) at the rate of 350 ml ha-1 (at the fifth trifoliate, flowering, pod setting stages and unsprayed control), two rates of seed treatment with the fungicide Thiram (thiram- treated at the rate of 5 g kg-1 seed and non-treated) and three common bean varieties (Mexican 142, Awash-1 Abraham and Mashilla Integrated Variety, Seed Treatment, and Fungicide on Common Bean 113 and Awash Melka). The experiment was laid out as a randomized complete block design (RCBD) in a factorial arrangement and replicated three times per treatment. The treatments were assigned to each plot randomly. The experimental area was divided into 24 plots and each plot had size of 4 m x 2 m (=8 m2) with five rows each at the spacing of 40 cm apart and 10 cm between plants. The plots and adjacent replications were spaced at the distances of 1.0 and 1.5 m, respectively. Recommended amount of 100 kg ha-1 diammonium phosphate (DAP) fertilizer (consisting of 46 kg P2O5 and 18 kg N ha-1) was applied once at planting. 2.4. Seed Treatment The seeds of all common bean varieties (Mexican 142, Awash-1 and Awash Melka) were treated with the systemic fungicide Tebuconazole at the rate of 5 g kg-1 seed 24 hours before sowing. The untreated seeds from all common bean varieties served as control or check treatments. 2.5. Tebuconazole Foliar Fungicide Application Tebuconazole 430 SC (Orius 25 EW) was applied at a rate of 350 ml ha-1 with water spray volume of 100 L ha- 1 at different growth stages of the crop, i.e. from vegetative stage (5th trifoliate stage), flowering (1st flower stage) to the beginning of pod setting using a knapsack sprayer having 20 liters capacity. Control (check) plots were sprayed with pure water in the same manner with that of fungicide sprayed plots to prevent differences among plots due to variation in moisture. The fungicide- sprayed plots were treated three times at a 10-day interval starting from the above mentioned growth stage of the crop onwards. The timing of application of the fungicide spray varied according to the growth stage of the crop varieties from the 5th trifoliate stage to the start of pod setting. Fungicide drift between and among the treatments were prevented by covering the plots with plastic sheets. 2.6. Data Collection The first fungicide spray was applied 46 days after sowing. Seven days after the start of fungicide spraying, anthracnose severity assessment was started. Anthracnose severity was assessed from 18 pre-tagged plants of from three central rows in each plot every week. Evaluation of disease severity was performed using a 1 to 9 grade disease scale proposed by Schoonhoven and Pastor-Corrales (1987), where: 1 = leaf with no visible symptoms; 2 = few isolated small lesions on mid-veins in the lower leaf surfaces; 3 = a higher frequency of small lesions on mid-veins in the lower leaf surfaces; 4 = lesions in the mid-vein and occasionally in secondary leaf veins; 5 = many small lesions scattered on mid- and secondary veins; 6 = many small lesions as described in grade 5 in the lower and upper leaf surface; 7 = large lesions scattered over the leaf blade; 8 = many large, coalesced lesions accompanied by tissue breakdown and chlorotic or abscised leaf; and 9 = severely diseased or dead leaf. Then the anthracnose severity grades were converted, for further analyses into percentage severity index (PSI) using the formula developed by Wheeler (1969) as follows: (1) The area under disease progress curve (AUDPC) and growth curve models were developed for the disease progress data. AUDPC-values were calculated for each plot using the formula stated by Campbell and Madden (1990). ….(2) Where: n = represents the total number of assessment times, ti is the time of the ith assessment in days from the first assessment date, and xi is percentage of disease severity at ith assessment. Disease progress in time was studied by recording the severity of anthracnose at a 7-day interval right from appearance of first disease symptoms till the maturity of the crop in different varieties and treatments. Therefore, disease progress rate was calculated for each plot using the following formula (Van der Plank, 1963): (3) Where: DPR = Disease progress rate, and Y = Disease severity Yield and yield component data, including number of pods per plant, number of infected pods per plant, number of seeds per pod, hundred seed weight and seed yield (kg ha-1) were measured from the three middle rows. The number of pods per plant was determined as the average number of pods from ten randomly pre- tagged plants and the number of infected pods per plant was determined from the same plants as the average number of anthracnose-infected pods. The average number of seeds per pod was counted at harvest time from ten randomly pre-tagged plants, in ten randomly taken pods per plant. The seeds were sun-dried and weighed. Hundred seeds having the symptom of anthracnose infection were weighed and registered separately for all treatments. The weights of hundred seeds were measured from seeds randomly taken from the total seeds harvested from each plot. The seed yield per hectare in kilogram was estimated from seed yields of each plot (after adjusting to 10% seed moisture content) obtained from the three central rows. Abraham and Mashilla East African Journal of Sciences Volume 12 (2) 111-126 114 2.7. Data Analysis All the disease, yield and yield component data were subjected to analysis of variance (ANOVA) using general linear model (GLM) procedure of SAS statistical version 9.2 software (SAS, 2009). The least significant difference (LSD) test was used to separate differences in treatment means of main factor effects where significant variation was observed at 5% probability level. Lsmeans for significantly different interaction effects were separated by SAS model PLGLM800 (P=0.05) using Duncan’s Multiple Range Test (DMRT). The cost and benefit of each treatment was estimated from the marginal rate of return (MRR) that was computed by considering the variable cost available in the respective treatment. Variable costs included chemical costs and labor expenses for application of fungicides both for seed and foliar treatment. The yield and economic data were collected to compare advantages of seed treatment and foliar application in different treatments. Economic data encompassed input cost that varied, including cost for chemicals and labour during production time. Based on the data obtained, cost-benefit analysis was performed using partial budget analysis, which is a method of organizing data and information about the cost and benefits of various agricultural alternatives (CIMMYT, 1988). Before marginal analyses were carried out, dominance analysis was conducted for the treatments. A dominance analysis was thus carried out by first listing the treatments in order of increasing costs that varied. Any treatment that has net benefits that are less than or equal to those of a treatment with lower costs that varied is dominated and it was eliminated from further consideration (CIMMYT, 1988). 3. Results and Discussion 3.1. Bean Leaf Anthracnose Severity Anthracnose disease appeared on bean leaves 46 days after sowing. Consistent with this observation, Hirpha and Salvaraji (2016) reported that the disease appeared 48 days after sowing common bean at Ambo. The interaction effect of seed treatment with foliar fungicide spray times indicated that plots without any fungicide treatment had high PSI throughout the disease assessment periods that ranged from 27.89% at initial assessment to 66.17% at terminal disease assessment period. In a similar study, Amin et al. (2013) reported that seed treatment with mancozeb followed by carbendazim foliar spray, and seed treatment with carbendazim followed by foliar spray with carbendazim significantly reduced bean anthracnose severity (Table 1). The integrated effect of variety, seed treatment and foliar spray time generally exhibited significant (p ≤ 0.05) difference in PSI all over the disease assessment periods (Table 2, 3). All varieties, regardless of seed treatment, sprayed at the third leaf stage of the crop exhibited lower disease severity till 74 days after planting (DAS); however, they were infected by anthracnose after these days. The highest (38.8-86%) significant percentage severity index (PSI) was recorded for Awash- 1 variety without seed treatment, followed by no-foliar fungicide spray at all disease assessment periods. The combined treatment effect on all common bean varieties, and with and/or without seed treatment but sprayed at flowering stage showed the lowest PSI at the final disease assessment period (Table 3). 3.2. Anthracnose Severity on Pod The percent severity index (PSI) of pods was significantly (P ≤ 0.05) affected by integrated anthracnose management (Tables 2 and 4). Significant (P  0.01) variation was observed on pod percent severity index due to variety * seed treatment * foliar application time at all disease assessment periods (Table 4). Plots sown with seed-treated Awash Melka variety and sprayed with the fungicide at flowering stage of the crop resulted in significantly the lowest (20.9%) PSI in comparison to non-treated seeds of Awash-1 without foliar spray, which exhibited the highest (71.3%) pod PSI. Seed treatment and foliar spray at flowering stage resulted in 68, 53 and 37% pod severity reduction over the control plots, i.e. non-treated seeds and without foliar spray on each of Awash-1, Awash Melka and Mexican 142, respectively. Control plots of Awash-1 variety showed higher pod PSI than the other varieties at all assessment periods; however, PSI was lower for Awash Melka variety than for the other two varieties. Abraham and Mashilla Integrated Variety, Seed Treatment, and Fungicide on Common Bean 115 Table 1. The effect of common bean varieties integrated with foliar fungicide spray times on percentage severity index and AUDPC at Bako in 2014 main cropping season. Treatment component (Variety x Foliar spray time) Anthracnose percent severity index (PSI, %) AUDPC(%- days) 53 DAS 60 DAS 67 DAS 74 DAS 81 DAS 88 DAS Variety: Foliar spray: Awash Melka 5th trifoliate 19.564 19.564 19.564C 22.826 F 31.236 EF 34.475 D 603.858 FG Flowering 20.864 22.130 22.301C 22.568 F 23.075 G 23.639 F 514.558 FG Pod setting 23.001 27.817 29.771B 32.156 DE 33.210 EF 33.463 D 908.848 DE Control 25.570 33.263 35.900B 49.216 B 55.964 B 63.062 B 1674.383 B Awash-1 5th trifoliate 20.174 20.174 21.619C 29.716 E 35.839 DE 42.399 C 795.782 EF Flowering 20.013 20.264 20.687C 21.628 F 22.840 G 24.753 EF 476.389 G Pod setting 25.207 33.087 34.697B 36.783 CD 42.067 CD 42.362 C 1248.765 C Control 29.676 38.117 49.125A 56.834 A 65.537 A 71.702 A 2071.193 A Mexican 142 5th trifoliate 20.275 20.549 20.726C 23.141 F 27.823 FG 31.314 DE 573.971 FG Flowering 20.275 21.478 22.559C 23.050 F 24.487 G 26.072 EF 537.963 FG Pod setting 26.169 33.211 34.455B 41.062 C 45.791 C 47.466 C 1360.391 C Control 21.644 27.403 31.266B 35.638 CD 40.817 CD 45.881 C 1113.735 CD LSD (0.05) Ns Ns 6.235 5.342 6.280 7.088 296.620 SE(±) 1.745 2.249 2.190 1.877 2.206 2.490 104.199 Seed treatment: Foliar spray: Treated 5th trifoliate 20.062 20.184 D 21.029C 26.935 C 31.740 D 35.507 C 678.395 C Flowering 20.338 21.079 D 21.702C 22.275 D 22.906 E 23.666 D 494.753 C Pod setting 25.611 33.229AB 34.252B 36.969 B 40.137 C 40.984 C 1223.800 B Control 23.368 27.388 C 31.131B 40.616 B 46.332 B 54.260 B 1290.775 B Untreated 5th trifoliate 19.947 20.007 D 20.244C 23.520 CD 31.526 D 36.618 C 637.346 C Flowering 20.430 21.503 D 21.996C 22.556 CD 24.029 E 25.977 D 524.520 C Pod setting 23.974 29.514BC 31.696B 36.365 B 40.575 C 41.210 C 1121.536 B Control 27.893 38.468 A 46.396A 53.843 A 61.880 A 66.170 A 1948.765 A LSD (0.05) Ns 5.227 5.091 4.362 5.127 5.787 242.189 SE(±) 1.425 1.836 1.788 1.532 1.801 2.033 85.078 Note: Means followed by the same or no letter within a column are not significantly different from each other at 0.05 probability level, DMRT test. Abraham and Mashilla East African Journal of Sciences Volume 12 (2) 111-126 116 Table 2. Mean squares from analysis of variance for disease parameters of bean anthracnose as influenced by variety, seed treatment and foliar fungicide spray time. Source DF Foliage PSI DPR Pod PSI Foliage AUDPC 53 DAS 88 DAS 60 DAS 88 DAS 67 DAS 88 DAS Model 25 51.639** 666.053 Ns 0.00202** 0.00075** 2182.58** 97114.93** 856224.40** Variety (A) 2 20.567 Ns 412.740 Ns 0.00007 Ns 0.00056** 2661.17** 145442.83** 454624.48** Seed treatment (B) 1 9.229 Ns 272.314 Ns 0.00146 Ns 0.00043** 555.56 Ns 180505.14** 333472.22* Foliar spray time (C) 3 153.564** 3927.266 Ns 0.01184** 0.00463** 1172.86** 466359.58** 4626224.11** Rap 2 27.700 Ns 53.886 Ns 0.00011 Ns 0.00006 Ns 12587.99** 8253.96 Ns 111647.97 Ns A x B 2 40.069 Ns 147.976* 0.00007 Ns 0.00007 Ns 550.99** 97430.62** 178710.21 Ns A x C 6 31.362 Ns 376.596** 0.00029 Ns 0.00041** 294.92 Ns 24083.90** 452835.87** B x C 3 31.695 Ns 131.943** 0.00250** 0.00009* 727.04** 9577.74 Ns 557813.01** A x B x C 6 60.188** 118.769* 0.00064 Ns 0.00004 Ns 12.003 Ns 28799.64** 218840.96** Error 46 18.268 37.196 0.00041 0.00002 137.250 5546.630 65144.56 Total 71 Mean 22.700 40.550 0.0262 0.0245 23.457 584.639 989.986 R2 60.570 90.680 72.29 94.76 89.63 90.490 87.72 Note: *= significant at p≤0.05; ** = highly significant p≤0.01; Ns: non-significant; PSI= percentage severity index; DPR= disease progress rate and AUDPC= area under disease progress curve. Table 3. Interaction effect of variety x seed treatment x foliar fungicide spray time on anthracnose percentage severity index at different anthracnose assessment periods on foliage at Bako in 2014 main cropping season. Variety Seed treatment Foliar Leaf severity index (%) AUDPC 53 DAS 60 DAS 67 DAS 74 DAS 81 DAS 88 DAS (%-days) Awash Melka Treated Trifoliate 19.657 C 19.657 G 19.657 H 25.464 G-J 32.453 35.762 F-I 648.87 FG Flower 21.1670 BC 22.345 FG 22.516 D-H 22.701 IJ 22.701 23.363 L 517.80 FG Pod 23.142 BC 27.966 C-G 29.499 B-G 31.366 E-H 32.435 32.940 H-L 900.21 D-F Non 27.490 B 34.153 BC 36.562 B 48.679 B 52.938 64.837 B 1668.62B Untreated Trifoliate 19.471 C 19.471 G 19.471 H 20.189 J 30.020 33.188 H-L 558.85 FG Flower 20.560 BC 21.915 FG 22.086 E-H 22.434 IJ 23.450 23.914 KL 511.32 FG Pod 22.861 BC 27.667 C-G 30.043 B-F 32.946 EFG 33.985 33.985 G-K 917.49 D-F Non 23.650 BC 32.374 BCD 35.237 B 49.752 B 58.991 61.288 BC 1680.14 B Mexican 142 Treated Trifoliate 19.838 C 20.204 FG 20.382 H 22.687 IJ 26.957 27.885 I-L 536.52 FG Flower 19.657 C 20.200 FG 21.420 F-H 21.594 IJ 22.791 23.428 L 472.43 G Pod 27.342 B 37.304 B 37.777 B 43.819 BC 49.079 50.877 DE 1540.43 BC Non 22.068 BC 23.053 EFG 26.174 C-H 29.232 F-I 34.028 40.540 F-H 832.51 E-G Untreated Trifoliate 20.712 BC 20.893 FG 21.071 GH 23.594 IJ 28.689 34.744 G-J 611.42 FG Flower 20.893 BC 22.756 EFG 23.697 D-H 24.507 HIJ 26.184 28.715 I-L 603.50 FG Pod 24.995 BC 29.118 B-F 31.13 BCD 38.304 CDE 42.503 44.055 EFG 1180.35C-E Non 21.220 BC 31.752 B-E 36.358 B 42.044 BCD 47.605 51.222 CDE 1394.96 BC Awash-1 Treated Trifoliate 20.691 BC 20.691 FG 23.049 D-H 32.656 EFG 35.809 42.875 E-H 849.79 D-G Flower 20.189 C 20.691 FG 21.169 GH 22.531 IJ 23.227 24.206 KL 494.03 FG Pod 26.349 BC 34.418 BC 35.481 B 35.722 DEF 38.898 39.135 FGH 1230.76 C-E Non 20.545 BC 24.957 D-G 30.657 B-E 43.936 BC 52.030 57.404 BCD 1371.19 BC Untreated Trifoliate 19.657 C 19.657 G 20.189 H 26.776 G-J 35.868 41.923 E-H 741.77 FG Flower 19.838 C 19.838 G 20.204 H 20.726 J 22.452 25.301 JKL 458.75 G Pod 24.065 BC 31.757 B-E 33.914 BC 37.844 CDE 45.236 45.590 EF 1266.77B-D Non 38.808 A 51.277 A 67.593 A 69.733 A 79.044 86.001 A 2771.19 A SE(±) 2.468 3.180 3.097 2.654 3.120 3.521 147.36 LSD (0.05) 7.025 9.053 8.817 7.555 Ns 10.024 419.484 Note: Means followed by the same or no letter within a column are not significantly different from each other at 0.05 probability level, DMRT test Abraham and Mashilla Integrated Variety, Seed Treatment, and Fungicide on Common Bean 117 3.3. Area under Disease Progress Curve (AUDPC) Interaction of variety * foliar spray, and seed treatment * foliar spray showed significant foliage AUDPC (Tables 1). However, the interaction effect of variety * seed treatment showed no significant difference. Awash-1 sprayed at flowering showed the lowest (476.389%-days) foliage AUDPC of all the other variety * foliar spray interactions. However, the highest AUDPC of 2071.193 and 1674.383%-days were observed on the foliage of control plots of Awash-1, and Awash Melka, respectively. This current result agrees with the findings of Mohammed and Somsiri (2005) who reported that the foliage AUDPC value was higher for the variety Awash-1 than Mexican 142. AUDPC was also significantly different among common bean varieties based on their reaction to the disease, in which the susceptible variety produced the highest foliage AUDPC, while the values were the lowest in resistant varieties (Sharma et al., 2008). Hirpha and Selvaraj (2016) also indicated that foliar fungicide application reduced AUDPC value on every variety. Foliage AUDPC calculated for plots from untreated seeds and not receiving any foliar fungicide sprays showed significantly (p≤0.05) highest (1948.765%- days) values of all the rest seed treatment and foliar fungicide spray combinations. However, the lowest 494.753 and 524.52%-days foliage AUDPC values were calculated from plots sown with seeds treated and sprayed at flowering, and untreated seeds but sprayed at flowering, respectively. Similar to the results of the current study, Amin et al. (2013) reported that interaction of seed treatment with foliar fungicide sprays significantly differed in foliage AUDPC values; generally plots from treated-seeds and followed by spray with foliar fungicide had significantly reduced foliage AUDPC values. The combined effect of variety *seed treatment* foliar spray time showed highly significant (P  0.01) difference in the area under disease progress curve (Table 2). The lowest most significant foliage AUDPC value (458.745%-days) was calculated from plots of the variety Awash-1, without seed treatment and sprayed at flowering, followed by AUDPC values of 472.428 and 494.033%-days that resulted from plots sown with treated-seeds of Mexican 142 and Awash-1, respectively, and both sprayed at flowering (Table 3). The highest foliage AUDPC value (2771.193%-days) was calculated from data recorded from non-seed treated and unsprayed Awash-1, followed by AUDPC value (1680.144%-days) on Awash Melka, without seed treatment and unsprayed plots. The three-way interaction effects of variety, seed treatment, and foliar fungicide spray showed significant differences on pod AUDPC values (Table 2 and 3). Significantly the highest pod AUDPC value (1150.25%- days) was calculated from plots sown with non-treated seeds of Awash-1 without foliar spray, followed by AUDPC value (919.45%-days) on plots sown with non-treated seeds of Mexican 142 without foliar spray. However, the lowest pod AUDPC value (435.06%- days) was calculated from plots sown with treated seeds of Awash Melka and sprayed at flowering of the crop variety (Table 3). Thus, integrated disease management options, rather than using a single component strategy alone, proved to be a more effective disease management option for sustainable bean production than using a single tactic alone. 3.4. Anthracnose Progress Rate on Common Bean Varieties The interaction effect of variety with foliar fungicide spray, and seed treatment with foliar fungicide spray were significant from 67 DAS assessment period onwards; however, the interaction effect of seed treatment with foliar fungicide spray was not significantly (P ≤ 0.05) different at 60 DAS (Table 2). The interaction effect of variety * seed treatment, and variety * seed treatment * foliar spray were not significant. Variety with foliar fungicide spray interaction resulted in significantly higher (0.0643 units- day-1) anthracnose progress rate on Awash-1 variety at 67 DAS than the interaction effect of the same variety without foliar spray. Awash Melka variety sprayed at fifth trifoliate stage till 67 DAS and Awash-1 at 60 DAS did not show any increase in disease progress rate (Figure 2). The analysis of variance revealed the occurrence of higher disease progress rates, i.e. 0.0584, 0.0471 and 0.0310 units-day-1 at the final disease assessment period on the control plots of Awash-1, Awash Melka and Mexican 142 varieties, respectively, than the treated plots of each variety. The maximum protected plot of Awash Melka sprayed at flowering reduced anthracnose progress rate 11 times more than the plots under natural condition (non-sprayed control plots), while the maximum protected plots of Awash-1 and Mexican 142 varieties sprayed with tebuconazole at flowering reduced disease progress rate seven and three times, respectively, more than the plots of the same varieties under natural conditions, i.e. without any treatment (Figure 4). Generally, anthracnose progress rates at 74 DAS disease assessment period onwards were lower on all bean varieties sprayed with tebuconazole at flowering stages than the disease progress rates of all the interactions due to other treatment combinations (Figure 3). Seed treatment and foliar fungicide spray at flowering significantly reduced anthracnose progress rate eight times more than the anthracnose progress rate on plots sown with treated-seeds but without foliar fungicide spray, while foliar spray alone reduced anthracnose progress rate six times more than plots sown from non- treated seeds and unsprayed with tebuconazole. Similar to the results of this study, Amin et al. (2013) reported that disease progress rate was significantly affected by seed treatment and foliar fungicide spray interaction at Haramaya. Abraham and Mashilla East African Journal of Sciences Volume 12 (2) 111-126 118 Table 4. Interaction effect of varieties, seed treatment and foliar spray times on pod percentage severity index (PSI) and AUDPC at Bako in 2014 main cropping season. Seed treatment Foliar Pod anthracnose severity index (%) AUDPC (%-days) 67 DAS 74 DAS 81 DAS 88 DAS Awash Melka: Treated Trifoliate 19.47 G 19.47 G 22.28 IJ 22.59 IJ 439.44 J Flower 19.84 G 20.89 FG 20.89 J 20.89 J 435.06 J Pod 20.90 FG 21.24 FG 22.20 IJ 22.20 J 454.88 J Non 25.03 CDE 37.48 BC 39.12 B-E 39.37 CD 761.71 CDE Untreated Trifoliate 19.47 G 19.47 B 21.54 J 22.53 IJ 434.06 J Flower 19.47 G 21.58 FG 24.21 HIJ 24.51 G-J 474.50 IJ Pod 20.55 FG 21.26 FG 22.30 IJ 22.30 IJ 454.91 J Non 21.54E FG 30.81 D 33.09 D-G 33.38 DE 639.53 EFG Mexican 142: Treated Trifoliate 19.47 G 21.22 FG 24.17 HIJ 24.74 F-J 472.45 IJ Flower 19.47 G 19.84 G 21.61 J 22.30 IJ 436.34 J Pod 25.46 CD 26.65 DEF 30.34 F-I 30.34 E-G 594.24 F-I Non 23.88 DEF 29.15 DE 31.53 E-H 31.53 EF 618.61 FGH Untreated Trifoliate 19.47 G 21.57 FG 26.96 G-J 29.76 E-H 512.04 HIJ Flower 20.53 FG 22.87 FG 26.77 G-J 27.05 E-J 513.97 HIJ Pod 22.44 D-G 24.75 EFG 27.08 G-J 27.34 E-J 536.96 G-J Non 33.88 B 44.34 A 46.30 B 47.54 B 919.45 B Awash-1: Treated Trifoliate 19.84 G 20.53 G 22.86 IJ 26.36 F-J 465.40 J Flower 19.47 G 20.85 G 21.91 J 22.28 IJ 445.44 J Pod 19.47 G 21.22 FG 22.56 IJ 22.90 HIJ 454.76 J Non 27.81 C 37.21 BC 45.35 BC 46.06 BC 836.48 BC Untreated Trifoliate 20.56 FG 32.30 CD 37.33 C-F 42.45 BC 707.90 DEF Flower 20.56 FG 20.56 G 24.61 HIJ 29.23 E-I 490.42 IJ Pod 25.86 CD 37.48 BC 40.84BCD 41.08 BC 782.53 CD Non 41.09 A 42.04 AB 66.08 A 71.32 A 1150.25 A LSD (0.05) 3.655 5.847 7.976 6.935 122.403 SE(±) 1.284 2.054 2.802 2.436 42.999 Note: According to DMRT, means followed by the same letter(s) within a column are not significantly different at 5% probability level. Figure 2. Interaction effect of seed treatment with foliar fungicide spray on anthracnose progress rate at Bako in 2014 main cropping season. Figure 3. Interaction effect of variety with foliar fungicide spray on anthracnose progress rate at Bako during 2014 main cropping season. Abraham and Mashilla Integrated Variety, Seed Treatment, and Fungicide on Common Bean 119 3.5. Effect of Variety, Seed Treatment, Foliar Spray and Their Interaction on Yield and Yield Components 3.5.1. Pod per Plant, Infected Pod per Plant, and Seed per Pod Main effects of variety, seed treatment and foliar fungicide spray showed highly significant (P ≤ 0.01) differences on the number of pods per plant and infected seed per pod. However, pod infection per plant was significantly (P ≤ 0.01) affected by variety and foliar fungicide spray (Table 5). The highest (16.958) mean number of pods per plant was observed for the variety Awash-1, while Awash Melka and Mexican 142 produced lower pod number than Awash-1, i.e. 13.542 and 14.875 pods per plant, respectively. Also, plots sown with treated-seeds produced significantly higher (17.056) pod mean number per plant than plots sown with untreated seeds. Plots sprayed with foliar fungicide at the fifth trifoliate stage gave significantly higher number of pods per plant than the control plots, followed by plots sprayed at flowering stage (Figure 4). Similar to this result, Amin et al. (2014) reported that the number of pods per plant was significantly different from foliar fungicide- sprayed plots and plots sown with bioagent-treated- seeds along with non-spray fungicide. But, contrary to this finding, Amin et al. (2013) reported that the number of pods per plant was non-significant and did not differ from plots sown with treated-and untreated- seeds, and foliar sprayed and non-sprayed plots. Figure 4. Effect of variety, seed treatment and foliar spray on number of pods per plant and number of seeds per pod at Bako in 2014 main cropping season. Note: According to DMRT, means followed by the same letter(s) within a similar colored graphs are not significantly different at 5% probability level. Table 5. Mean squares of common bean morphological and yield related data parameters as influenced by integrated anthracnose management options at Bako in 2014 main cropping season. Source DF Mean squares (MS) values IP NSP PP Model 25 1330.118** 0.298* 32.640** Variety (A) 2 2329.542** 1.120** 73.789** Seed treatment (B) 1 130.681 Ns 0.405 Ns 288.400** Foliar spray (C) 3 6796.125** 0.323 Ns 43.858** Rep 2 32.042 Ns 0.058 Ns 0.691 Ns A x B 2 433.681** 0.238 Ns 1.934 Ns A x C 6 433.986** 0.332 Ns 29.659** B x C 3 132.384 Ns 0.141 Ns 15.937* A x B x C 6 690.384** 0.139 Ns 2.907 Ns Error 46 77.998 0.163 4.494 Total 71 R2 90.26 49.9 79.788 Mean 31.625 5.500 15.054 Note: DF = Degree of freedom; IP = infected pod per plant; NSP = Number of seeds per pod and PP = pod per plant; ** Highly significant at p ≤ 0.01; * Significant at p ≤ 0.05; Ns= non-significant. Abraham and Mashilla East African Journal of Sciences Volume 12 (2) 111-126 120 Plots sown with treated-seeds of Awash Melka variety and sprayed with tebuconazole at flowering stage reduced pod infection by more than 93, 93 and 94% over the plots sown with untreated seeds and unsprayed Awash-1 and Mexican varieties and treated- seeds and non-sprayed Awash Melka varieties, respectively. (Tables 5 and 7). Pod infection significantly (p≤0.05) varied among common bean varieties even without any fungicide treatment. In this connection, Awash Melka variety without any seed treatment showed lower (38.67%) pod infection, while 75 and 71.3% pod infections were recorded for the varieties Awash-1 and Mexican 142 plots, respectively, that did not receive any fungicide treatment. Pod infection on the susceptible common bean variety ranged from 45.60 to 55.95% during favorable environment for pathogens to cause disease development (Hanan et al., 2009). 3.5.2. Effect of Integrated Anthracnose Management Options on Hundred Seed Weight of Infection-Free and Infected-Seeds Combined effect of common bean variety with foliar fungicide spray significantly affected hundred infected- seed weight; however, combined effect of variety with thiram seed treatment, foliar fungicide spray with seed treatment, and integrated effects of variety with seed treatment with foliar fungicide spray resulted in non- significant difference in weights of hundred infected- seeds (Table 6). The result indicated that Awash-1 variety without foliar fungicide spray significantly lowered (10.9 g) 100 infected seed weight. However, the infected seeds of the variety Awash Melka sprayed at pod setting and Mexican 142 variety sprayed at flowering showed higher hundred seed weight than that of Awash-1 (Table 6). 3.5.3. Effect of Integrated Anthracnose Management Options on Seed Yield The two-way interaction of variety with seed treatment, variety with foliar spray, and seed treatment with foliar spray showed a significant difference in bean seed yield (Table 6). Plots sown with treated seeds of Awash Melka produced the highest significant seed yield (1912.750 kg ha-1) of all treatments. Similarly, the highest, i.e. average seed yields (2096.493 and 2071.486 kg ha-1,) were obtained from bean plots sown with treated and untreated seeds and sprayed at flowering stage, respectively, whereas plots sown with non-treated seeds and non-sprayed with fungicide showed significantly lower (1049.354 kg ha-1) average seed yield, followed by the seed yield (1419.920 kg ha-1) from plots sown with treated-seeds and non- sprayed plots (Table 6). Consistent with the results of this study, Amin et al. (2013) reported that the combined effect of benlate (benomyl) as a seed treatment and difenoconazole (Score 250 EC) effectively reduced anthracnose severity and increased the yield per plot. Mexican 142 sprayed at the fifth trifoliate stage, and Awash-1 and Awash Melka sprayed at the flowering stage produced the highest respective seed yields of 2226.770, 2197.88 and 2149.62 kg ha-1 of all other treatment combinations of variety with foliar fungicide sprays. On the contrary, Awash-1 without foliar fungicide spray produced the lowest (948.32 kg ha-1) seed yield. Foliar fungicide spray at flowering stage increased seed yield of Awash-1 variety by 56% over the unsprayed (control) plots (Table 6). Three-way interactions of variety, seed treatment and foliar spray significantly differed in seed yield among the treatment combinations (Table 7). The seed yield obtained from plots sown with treated seeds of Mexican 142 variety and sprayed at the trifoliate stage was the highest (2354.07 kg ha-1), followed by 2156, 2239.76 and 2175.99 kg ha-1 seed yields of Awash-1 sown with treated and non-treated seeds and sprayed at flowering stage, and Awash Melka without seed treatment and sprayed at flowering stage, respectively. Foliar spray at flowering stage alone increased seed yield by more than 67% for Awash-1 variety over the control plots of the same variety (Table 7). The minimum seed yield advancement by 38% was recorded from Awash-1 plots sown with seed-treated but without foliar fungicide spray as compared with its own control plots of the three-way interaction combinations. Abraham and Mashilla Integrated Variety, Seed Treatment, and Fungicide on Common Bean 121 Table 6. Two-way interaction effect of common bean varieties, seed treatment and foliar fungicide spray time on yield and yield related parameters at Bako in 2014 main cropping season. Components: Pod per plant (No.) 100 infected seed wt (g) Yield (kgha-1) Seed treatment x Variety: Seed treatment: Variety: Treated Awash Melka 15.258 14.796 1912.750 A Awash-1 19.233 12.834 1598.607 C Mexican 142 16.675 13.013 1793.011 B Untreated Awash Melka 11.575 13.769 1680.616 C Awash-1 14.575 12.696 1595.708 C Mexican 142 13.008 12.692 1606.930 C LSD (0.05) NS NS 101.289 SE (±) 0.601 0.414 35.582 Seed treatment x Foliar spray Seed treatment: Foliar spray: Treated 5th trifoliate 19.111 A 13.463 1945.010 B Flowering 18.611 A 14.896 2096.493 A Pod setting 14.289 BC 13.400 1611.066 D Control 16.211 B 12.433 1419.920 E Untreated 5th trifoliate 14.444 BC 13.457 1765.225 C Flowering 12.244 DE 13.907 2071.486 A Pod setting 11.722 E 13.176 1624.940 D Control 13.800 CD 11.670 1049.354 F LSD (0.05) 2.011 NS 116.958 SE (±) 0.707 0.477 41.086 Variety x Foliar Spray Variety Foliar spray Awash Melka 5th trifoliate 13.383 DE 14.418 AB 1845.490 BC Flowering 14.267 CD 14.488 AB 2149.616 A Pod setting 11.467 EF 15.338 A 1810.926 BC Control 14.550 CD 12.886 BCD 1380.701 DE Awash-1 5th trifoliate 19.333 A 12.269 CDE 1493.092 D Flowering 16.533 BC 15.221 A 2197.883 A Pod setting 17.467 AB 12.671 CD 1749.335 C Control 14.283 CD 10.899 E 948.319 F Mexican 142 5th trifoliate 17.617 AB 13.693 ABC 2226.770 A Flowering 15.483 BCD 13.495 BCD 1904.471 B Pod setting 10.083 F 11.854 DE 1293.748 E Control 16.183 BC 12.369 CDE 1374.891 DE LSD (0.05) 2.464 1.665 143.244 SE (±) 0.865 0.585 50.320 Note: Means followed by the same or no letter (s) in the same column are not significantly different from each other at p≤0.05, DMRT Abraham and Mashilla East African Journal of Sciences Volume 12 (2) 111-126 122 Table 7. Interaction effects of common bean variety, seed treatment and foliar fungicide spray time on infected pod per plant and seed yield at Bako in 2014 main cropping season. Variety Seed treatment Foliar spray Infected pod per plant (%) Seed yield (kg ha-1) Awash Melka Treated Trifoliate 13.000 HI 1918.983DEF Flower 4.333 I 2123.245 BCD Pod 9.333 HI 2035.057 BCD Non 73.000 A 1573.716 HI Untreated Trifoliate 23.333 E-H 1771.998 FGH Flower 9.667 HI 2175.986 ABC Pod 9.333 HI 1586.794 GHI Non 38.667 D 1187.686 M Mexican 142 Treated Trifoliate 28.667 D-G 2354.074 A Flower 23.000 E-H 2010.231 CDE Pod 14.000 HI 1298.336 J-M Non 31.000 DEF 1509.400 IJ Untreated Trifoliate 30.000 DEF 2099.465 BCD Flower 21.667 E-H 1798.711 EFG Pod 21.667 E-H 1289.160 KLM Non 71.333 AB 1240.383 LM Awash-1 Treated Trifoliate 58.333 BC 1561.973 HI Flower 33.667 DE 2156.003 ABC Pod 18.000 F-I 1499.805 IJK Non 57.000 C 1176.645 M Untreated Trifoliate 58.000 BC 1424.212 I-L Flower 15.000 GHI 2239.762 AB Pod 22.000 E-H 1998.865 CDE Non 75.000 A 719.992 N LSD (0.05) 14.515 202.578 SE(±) 5.099 71.163 Note: Means followed by different letters within the same column are significantly different from each other and without letters are not significant at p≤0.05, DMRT. 3.6. Cost-Benefit Analysis in Bean Anthracnose Management Partial budget analysis of marginal cost and marginal benefit depicted the highest (ETB 32,775.67 ha-1) marginal benefit from Mexican 142 plots sown with treated-seed and foliar fungicide-spray at the fifth trifoliate stage. However, Awash-1 and Awash Melka varieties sown without seed treatment and sprayed with tebuconazole at flowering stage resulted in the highest marginal benefits of ETB 31,562.57 and 30,644.20 ha-1, respectively. In addition, the marginal rates of return were calculated for the significant treatments under dominant analysis for comparison of the treatment cost/benefit of the treatments (Table 8). For the variety Awash-1, plots sown with untreated seeds and sprayed with fungicide at flowering stage exhibited that for every one ETB incurred or invested on foliar fungicide spray at this stage additional ETB 30.72 was obtained in return, followed by ETB 25.69 from plots without seed treatment and sprayed with fungicide at pod setting. Generally, Awash-1 without seed treatment and with foliar fungicide spray at flowering stage resulted in a higher marginal rate of return than the other two common bean varieties, i.e. Awash Melka and Mexican 142. Similar to the findings of this study, Hirpha and Selvaraji (2016) indicted that Awash-1 sprayed with fungicide had high marginal rate of return. On the other hand, sowing seeds after treating with the fungicide resulted in lower rates of return than sowing without treatment because additional costs were incurred for the purchase of fungicide for seed treatment (Table 8). Abraham and Mashilla Integrated Variety, Seed Treatment, and Fungicide on Common Bean 123 Table 8. Cost-benefit analysis of common bean production as influenced by anthracnose management options at Bako in 2014 main cropping season. Seed treatment Foliar spray Seed yield (kg ha-1) Adj. seed yield (kg ha- 1) Gross return (ETB ha-1) Marginal cost (ETB ha-1) Marginal benefit (ETB ha-1) MRR (%) Awash Melka Treated Trifoliate 1918.98 1727.085 27633.4 1123.00 26510.36 --- Flowering 2123.25 1910.921 30574.7 1123.00 29451.73 --- pod setting 2035.06 1831.551 29304.8 1123.00 28181.82 --- None 1573.72 1416.344 22661.5 433.00 22228.51 1183.79 Untreated Trifoliate 1772.00 1594.798 25516.8 690.00 24826.77 1119.43 Flowering 2175.99 1958.387 31334.2 690.00 30644.20 1962.54 pod setting 1586.79 1428.115 22849.8 690.00 22159.83 --- None 1187.69 1068.917 17102.7 0.00 17102.68 0.00 Mexican 142 Treated Trifoliate 2354.07 2118.667 33898.7 1123.00 32775.67 1328.06 Flowering 2010.23 1809.208 28947.3 1123.00 27824.33 --- pod setting 1298.34 1168.502 18696.0 1123.00 17573.04 --- None 1509.40 1358.460 21735.4 433.00 21302.36 794.65 Untreated Trifoliate 2099.47 1889.519 30232.3 690.00 29542.30 1692.87 Flowering 1798.71 1618.840 25901.4 690.00 25211.44 1065.21 pod setting 1289.16 1160.244 18563.9 690.00 17873.90 --- None 1240.38 1116.345 17861.5 0.00 17861.52 0.00 Awash-1 Treated Trifoliate 1561.97 1405.776 22492.4 1123.00 21369.41 --- Flowering 2156.00 1940.403 31046.4 1123.00 29923.44 --- pod setting 1499.81 1349.825 21597.2 1123.00 20474.19 --- None 1176.65 1058.981 16943.7 433.00 16510.69 1418.66 Untreated Trifoliate 1424.21 1281.791 20508.7 690.00 19818.65 1369.68 Flowering 2239.76 2015.786 32252.6 690.00 31562.57 3071.69 pod setting 1998.87 1798.979 28783.7 690.00 28093.66 2568.95 None 719.99 647.9928 10367.9 0.00 10367.88 0.00 Note: Numbers written in columns of marginal rate of return (MRR) were treatments that showed significant differences in dominance analysis; average market price of bean ETB 16 kg-1 4. Conclusions The results of this study demonstrated that seed treatment and foliar spray of common bean plants with the contact fungixide Thiram at the rate of 5 g kg-1 at flowering stage significantly reduced foliage anthracnose percent severity index (PSI) by 54.26, 61.88 and 71.85% over the respective control plots of all three varieties tested (i.e., sown with non-treated seed without any earlier foliar sprays). The results revealed that Mexican 142 common bean variety sown from treated-seed and sprayed with tebuconazole at the fifth trifoliate stage produced the highest (2354.074 kg ha-1) seed yield, followed by seed yield (2239.76 kg ha- 1) of the variety Awash-1 sown from non-treated seed and sprayed at flowering stage. The economic analysis of the seed treatment with thiram at the rate of 5 g kg-1 seed indicated the highest (3071%) marginal rate of return (MRR) from the variety Awash-1, followed by the same variety with MRR of 2568% without seed treatments but sprayed at flowering and pod setting stages, respectively, as well as Awash Melka (1962%) MRR without seed treatment but sprayed at flowering stage. Awash-1 without seed treatment but sprayed at pod setting gave 2568% MRR, but 13% of the seeds had blemishes on their surfaces due to anthracnose resulting in low seed quality. Therefore, Awash-1 and Awash Melka without seed treatment but with a foliar spray treatment with tebuconazole at the rate of 350 ml ha-1 at the water spray volume of 100 L ha-1 at flowering stage that resulted in optimum yield and economic benefits of the crop are recommended as options for the management of common bean anthracnose. This implies that common bean farmers in the study area can enhance the productivity of common bean with the integrated cultivation of Awash-1 and Awash Melka common bean varieties with the spray of the fungicide at the aforementioned rate. Similarly, further research into seed treatment with different fungicides, testing the efficacies of more fungicides, application rates and frequencies in multi- locations over seasons is desirable to design a consolidated integrated bean anthracnose management Abraham and Mashilla East African Journal of Sciences Volume 12 (2) 111-126 124 options for sustainable common bean production in the study area and elsewhere that have similar agroecologies. Future research should focus also on breeding for resistance by transferring resistance genes into improved market-type elite common bean varieties. 5. Acknowledgements This paper was extracted from a Master’s thesis, and Haramaya University is acknowledged for facilitating the study. The authors thank the Oromia Agricultural Research Institute for funding the research project and Bako Agricultural Research Center for facilitating the mobilization of resources to accomplish the task. Special thanks are also extended to all staff members of the Pulse and Horticulture Research Team at Bako Agricultural Research Center for their unreserved assistance in managing the field trials and data collection. 6. References Aleligne K. 1990. Farm survey and on-farm research in haricot bean in the Middle Rift Valley of Ethiopia. pp. 3-7. In: Proceedings of a National Workshop on Research on Haricot Bean in Ethiopia, Addis Ababa, Ethiopia, 1-3 October, 1990. Allen, D. J., Ampofo, J. K. and Wortmann, C. S. 1996. Pests, diseases, and nutritional disorders of the common bean in Africa. A field guide. Centro International De Agricultural Tropical (CIAT); Technical Center for Agricultural and Rural Cooperation (TCA), Cali, (CIAT Publication no. 260). 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